It is known to provide a subsurface safety valve operated by a solenoid coil. U.S. Pat. No. 3,731,742 discloses in one form a safety valve which is moved mechanically to the open position by a well tool and is locked in the open position by a detent. The valve is triggered to the closed position by actuating a solenoid for releasing the detent. U.S. Pat. Nos. 4,191,248 and Re. 30,110 disclose subsurface solenoid actuated safety valves in which the solenoid mechanism performs the function of opening the valve and is fail-safe in that the valve will close in the event that electrical power is lost. However, these valves will undesirably close if various well forces overcome the power of the solenoid such as if the flow velocity through the well tubing increases or if well tools moving upwardly in the safety valve engage and cause the safety valve to close.
The present invention is directed to a fail-safe subsurface solenoid actuated well safety valve in which the solenoid, when energized, will move the valve to the open position and thereafter the valve is positively locked in the open position for eliminating the possibility that various forces in the well could overcome the force of the solenoid and undesirably close the valve.